1. Field of the Intention
The present invention relates to an air conditioning system, and more particularly to a system for circulating a fluid which can change a phase between a gas phase and a liquid phase by a difference of a specific gravity between a gas and a liquid between a heat source side machine and a plurality of user side machines disposed below the heat source side machine, so that each of the user side machines can at least perform a cooling.
2. Background Art
Conventional arts include, for example, a system as shown in FIG. 8 as an air conditioning system which does not need a power for transporting a phase-changeable fluid, that is, a fluid changing a phase between a liquid phase and a gas phase by outputting or inputting a latent heat. In this system, a heat source side machine 1 serving as a condenser is mounted at a high position of a building, and a liquid phase pipe 6 and a gas phase pipe 7 connect the heat source side machine with a heat exchanger 5 of a user side machine 4 mounted in a room to be air-conditioned disposed in a lower position than the heat source side machine. The system supplies a liquid which is heat-discharged and condensed in the heat source side machine 1 to the heat exchanger 5 of the user side machine 4 through the liquid phase pipe 6 by its own weight and on the contrary returns a gas which is heat-absorbed and evaporated by heat-exchanging with a warm air of the room in the user side machine 4 to the heat source side machine 1 through the gas phase pipe 7, thereby capable of performing a circulation. Accordingly, there are advantages such that a transporting power such as an electric pump is not necessary and a running cost at a time of performing a cooling can be reduced. In this case, reference numeral 8 denotes a flow control valve and reference numeral 9 denotes a blower.
Further, an air conditioning system as shown in FIG. 9 is disclosed in Japanese Patent Unexamined Publication No. 7-151359. In the air conditioning system having the above structure, the heat source side machine 1 disposed at a high position can supply a condensed refrigerant or an evaporated refrigerant, and reference numeral 30 denotes an electric pump and reference numerals 31 to 34 denote an opening and closing valve. These elements are connected by the liquid phase pipe 6 and the gas phase pipe 7 as shown in the drawing so as to form a closed circuit 3. The phase-changeable fluid sealed within the closed circuit 3 circulates between the heat source side machine 1 and the user side machine 4 so that the user side machine 4 can perform a cooling or a heating. In this case, reference numeral 35 denotes a liquid level sensor disposed in a side surface of the heat source side machine 1, which controls the electric pump 30 in such a manner as to make a refrigerant fluid stored in the heat source side machine 1 at a time of heating constant.
Accordingly, in the air conditioning system capable of performing a cooling operation and a heating operation as shown in FIG. 9, when the temperature of the room in which the user side machine 4 is mounted is high, in a state of stopping the electric pump 30, the opening and closing valves 31 and 32 are closed and the opening and closing valves 33 and 34 are opened, and further, the flow controlling valve 8 is also opened. Therefore, when the refrigerant sealed within the closed circuit 3 is condensed and cooled in the heat source side machine 1, the refrigerant fluid condensed in the heat source side machine 1 drops in the liquid phase pipe 6 by its own weight and flows into the heat exchanger 5 through the opening and closing valves 33 and 34 and the flow control valve 8.
Then, the refrigerant fluid flowing into the heat exchanger 5 absorbs the heat from the air within the room through the pipe wall of the heat exchanger so as to perform a cooling operation, and the refrigerant itself evaporates and flows into the gas phase pipe 7, thereby recirculating to the heat source side machine 1 of which pressure becomes lower by condensation of the refrigerant so as to form a natural circulation Accordingly, since the electric power for driving the electric pump 30 is not necessary in the summer time when the electric power consumption becomes maximum during a year, there is an advantage that the running cost can be reduced.
Further, in a state that the opening and closing valves 31 and 34 are closed and the opening and closing valves 32 and 33 are opened, and further, the flow control valve 8 is also opened, when the electric pump 30 is driven and the refrigerant sealed within the closed circuit 3 is condensed and cooled in the heat source side machine 1, the refrigerant fluid condensed in the heat source side machine 1 drops in the liquid phase pipe 6 by its own weight and the discharging force of the electric pump 30, and flows into the heat exchanger 5 through the flow control valve 8, thereby forcibly circulating the refrigerant for performing the cooling operation.
As mentioned above, in the case that the cooling operation is performed by driving the electric pump 30, there is an advantage that a sufficient amount of refrigerant fluid can be supplied to the heat exchanger 5 mounted in the higher floor which corresponds to the place immediately below the heat source side machine 1.
On the contrary, in the case that the temperature of the room in which the user side machine 4 is mounted is low, when the opening and closing valves 32 and 33 are closed and the opening and closing valves 31 and 34 are opened, and further, the flow controlling valve 8 is also opened, and in a state that the electric pump is driven, when the refrigerant sealed within the closed circuit 3 is heated and evaporated by the heat source side machine 1, the refrigerant gas evaporated in the heat source side machine 1 flows into the heat exchanger 5 through the gas phase pipe 7.
Then, the refrigerant gas flowing into the heat exchanger 5 discharges the heat to the air within the room through the pipe wall of the heat exchanger so as to perform a heating operation, and the refrigerant itself condenses and flows into the liquid phase pipe 6, thereby recirculating to the heat source side machine 1 through the opening and closing valves 34 and 31 by the electric pump 30. Accordingly, the heating by the user side machine 4 can be continued.
However, in the air conditioning system as shown in FIG. 8, since all the weight of the fluid which discharges the heat in the heat source side machine, is condensed and is stored in the liquid phase pipe acts as a pressure to the heat exchanger of the user side machine mounted on the lower floor, the fluid can be easily supplied, but to the heat exchanger of the user side machine mounted on the higher floor, since only the weight of the fluid stored in the liquid phase pipe disposed above the part acts as a pressure, the more difficult it is to supply the fluid, the higher floor the user side machine is mounted on, so that the cooling performance tends to be insufficient.
In order to solve this problem, it is possible to make the volume of the flow control valve of the user side machine mounted on the higher floor larger than the volume of the flow control valve of the user side machine mounted on the lower floor, so that the fluid is easily supplied to the flow control valve of the user side machine mounted on the higher floor. However, in this structure, it is necessary to prepare the user side machines having various kinds of volumes, so that the control in the work area becomes complex and the cost is increased. Accordingly, in the air conditioning system for basically performing a natural circulation of the phase-changeable fluid even in the case of using the user side machine having the same volume, it is necessary to provide a system capable of performing an optimum flow circulation.
Further, in this kind of air conditioning system, since the liquid discharged heat and condensed in the heat source side machine is supplied to the heat exchanger of the user side machine by its own weight, when the sudden heat load is generated at a time of starting the cooling, the fluid is evaporated in the heat exchanger of the user side machine at a short time and the pressure within the gas phase pipe is increased so that it is hard that the fluid flows into the heat exchanger, and further, the fluid flows backward in the flow control valve 8 so that the heat absorbing and evaporating phenomenon in the heat exchanger is stopped, thereby incapable of performing the cooling operation.
Further, in the air conditioning system as shown in FIG. 9, since the refrigerant gas heated and generated in the heat source side machine is supplied to the heat exchanger of the user side machine by the heated gas pressure, when the sudden heat load is generated at a starting time of the heating, the supply of the refrigerant gas is not good enough, so that so-called a sleep phenomenon of the refrigerant, that is, the condensed refrigerant is stored in the heat exchanger of the user side machine occurs, thereby blowing the unheated wind within the room. Since the amount of the refrigerant sealed within the closed circuit is constant, it is considered that the electric pump is stopped or the refrigerant from the user side machine is not returned to the heat source side machine- Accordingly, there is a problem that the pressure in the closed circuit locally increases more than necessity.
Still further, when the temperature of the open air is low, a lot of phase-changeable fluid is condensed within the pipe so that a so-called sleeping phenomenon occurs Accordingly, it is necessary to excessively charge within the pipe taking the sleeping phenomenon into consideration There is a problem that if the excess charge is not prepared, the circulating amount is insufficient so that a sufficient heating performance can not be obtained.
Furthermore, in the case of performing the cooling operation by naturally circulating the refrigerant in a state of stopping the electric pump, the electric power consumption in the summer in which the electric power is consumed at a maximum rate can be reduced so that reduction of the running cost can be realized. However, it is hard to supply a sufficient amount of refrigerant to the user side machine mounted on the higher floor which has a small difference in level from the place in which the heat source side machine is mounted In addition to this, even in the user side machine mounted on the same floor, in accordance with the difference in view of the pipe length and the arranging angle, there are a case that the refrigerant is easily supplied and a case that the refrigerant is hardly supplied, so that there is a problem that it is difficult to securely control the room temperature.
On the contrary, when the electric pump is driven, the sufficient amount of refrigerant can be supplied to the user side machine mounted on the higher floor so that the necessary cooling can be secured However, in this case, the electric power for driving the pump is necessary. Further, since the electric pump necessary in this case is a large size pump having a capacity of transporting the refrigerant fluid condensed in the user side machine at a time of heating to the heat source side machine mounted above, there is a problem that the electric power consumption is further necessary. Accordingly, there is a need for solving these problems.